Hi SMCK,
I don’t know what it means exactly either (other than perhaps referring to the spine decompressing and the discs rehydrating over the course of the night) and I didn’t see the terminology on the pages you linked. Do you have a link to where this term is used?
I don’t have any personal experience on any of these mattresses and there are too many variables involved with sleeping temperature relative to different people and mattress constructions to know for certain how hot or cool any mattress will sleep for any particular person (outside of actually measuring your sleeping temperature with testing equipment over the course of the night). There is more information in this link which I posted in my previous reply that can help you decide whether you may be more or less likely to sleep hot on any particular mattress based on the materials and components inside it.
The Dreamfoam is a softer memory foam mattress that is comparable to the Tempurpedic Cloud Luxe in terms of its softness/firmness. The Tuft & Needle is a polyfoam mattress that would probably feel firmer for most people.
As I mentioned in my previous replies … when you can’t test a mattress in person then the most reliable source of guidance will be a more detailed phone conversation with a knowledgeable and experienced online retailer or manufacturer who will be in the best position to help “talk you through” the options they have available that would likely be the best “match” for you based on the information you provide them, any local testing you have done, and the “averages” of their customers that are similar to you (see mattress firmness/comfort levels in post #2 here).
Phoenix